Minnesota Boiler License Practice Exam

Which of the following is NOT a way to define a boiler horsepower?

1. 10 square feet of heating surface

2. Boiler BTU input / 500,000

3. 10 kilowatts

4. All of the above

The correct answer is: Boiler BTU input / 500,000

To determine which choice does not correctly define boiler horsepower, it's important to understand the standard definitions and conversions related to boiler horsepower. Boiler horsepower is commonly defined in several ways, one of which is by the heating surface area. Specifically, 10 square feet of heating surface is often equated to one boiler horsepower because a certain amount of heating surface is necessary to generate steam efficiently. Another definition often used is based on thermal input, where one boiler horsepower is equal to a heating capability of approximately 33,475 BTUs per hour. The conversion from boiler BTUs to boiler horsepower is often simplified as 1 boiler horsepower equals the BTU input value divided by around 33,475, not 500,000. This means that translating BTU input directly to boiler horsepower using a factor of 500,000 is not standard practice and thus does not correctly describe boiler horsepower. The definition of 10 kilowatts is another valid conversion; kilowatts can be converted to horsepower using a straightforward formula. Since 1 boiler horsepower is close to 0.7457 kilowatts, the factor of 10 kilowatts can represent a certain number of horsepower but isn't a direct or common way to state one boiler horsepower. Therefore, the